Remaining carbon budgets specify the quantity of CO2 that can be emitted before a given warming level (such as the 1.5 °C target) is reached, and are thus of high interest to the public and policymakers. Yet, there are many sources of uncertainty which make it challenging to deduce this finite amount of CO2 emissions. The theoretical foundation of carbon budgets is based on the concept of the Transient Climate Response to cumulative CO2 Emissions (TCRE). This is the pathway-independent ratio of global warming per unit of cumulative CO2 emissions. However, accounting for non-CO2 forcings and changes in albedo or other Earth system feedbacks provides further challenges in calculating TCRE and the remaining carbon budgets.

This session aims to further our understanding of the climate response under different emission scenarios, and to advance our knowledge of associated carbon budgets consistent with meeting various levels of warming. We invite contributions that use a variety of tools, including fully coupled Earth System Models, Integrated Assessment Models, or simple climate model emulators. We welcome studies exploring different aspects related to carbon budgets and the TCRE framework, including: the governing mechanisms behind linearity of TCRE and its limitations, effects of different forcings and feedbacks (e.g. permafrost carbon feedback) and non-CO2 forcings (e.g. aerosols, and other non-CO2 greenhouse gases), estimates of the remaining carbon budget to reach a given temperature target (for example, the 1.5 °C warming level from the Paris Agreement), the role of pathway dependence, the climate-carbon responses to different emission scenarios (e.g. SSP scenarios, or idealized scenarios), and the behaviour of TCRE in response to artificial CO2 removal from the atmosphere (i.e. negative emissions). Contributions from the fields of climate policy and economics focused on applications of carbon budgets are also encouraged.

Accurate and precise atmospheric measurements of greenhouse gas (GHG) concentrations reveal the rapid and unceasing rise of global GHG concentrations due to human activity. The resulting increases in global temperatures, sea-level, glacial retreat, and other negative impacts are clear. In response to this evidence, nations, states, and cities, private enterprises and individuals have been accelerating GHG reduction efforts while meeting the needs of global development. The urgency, complexity and economic implications of GHG reductions demand strategic investment in science-based information for planning and tracking emission reduction policies and actions. In response, the World Meteorological Organization (WMO) Global Atmosphere Watch Program (GAW) and its partners have initiated the development of an Integrated Global Greenhouse Gas Information System (IG3IS). IG3IS combines atmospheric GHG concentration measurements and human-activity data in an inverse modeling framework to help decision-makers take better-informed action to reduce emissions of greenhouse gases and pollutants that reduce air quality. This service is based on existing and successful measurement and analysis methods and use-cases for which the scientific and technical skill is proven or emerging.

This session intends to gather presentations from researchers and decision-makers (user-community) on the development, implementation and use of atmospheric measurement-based “top-down” and data-driven “bottom-up” GHG emission inventory estimates, and the combination of both approaches, explicit in space and time, to deliver actionable emissions information at scales where human activity occurs and emission reduction is most effective. This session will also showcase the new projects and efforts to develop “good-practice” standards under the World Meteorological Organization (WMO) Integrated Global Greenhouse Gas Information System (IG3IS), which is part of WMO’s commitment to science-based services.

Understanding the impact of climate change on natural and socio-economic outcomes plays an important role in informing a range of national and international policies, including energy, agriculture and health. Economic models of climate impacts used to guide policy rely on multiple components: projections of future climate change, damage functions, and policy responses, each of which comes with its own modelling challenges and uncertainties.

We invite research using process-based (e.g. Integrated Assessment Models) and empirical models of climate change to investigate future impacts, together with policy evaluation to explore effective mitigation, technology and adaptation pathways. Furthermore, we invite research on changes to, and new developments of climate-economic and econometric modelling.

Globally, there is increased concern for the potential impacts of extreme climate events in terms of losses and damage to people, assets & infrastructure, property and society as a whole. Plenty of evidence provided by, e.g., the Intergovernmental Panel on Climate Change (IPCC) and the scientific literature, but also by the insurance sector, supports these concerns, indicating clearly that both, overall and insured losses and damages are on the rise, and that a major part of these developments can be attributed to climate change.
New multi-hazard and multi-risk models, catastrophe (CAT) models, tools, and services aimed at providing reliable and probabilistic climate information to a broad range of public and economic sectors are currently being developed in close collaboration with users. Innovations in this regard can provide the means to, e.g., better understand costs and benefits of adaptation and more accurately underwrite risk by insurance and re-insurance companies, who serve as key implementers in increasing societies’ resilience and recovery from extreme events. Such services are crucial in order to facilitate effective and evidence-based adaptation planning by for example cities, regional authorities and other sectors.
This session invites contributions that: (1) highlight the current state-of-the-art in climate change hazard and risk assessment related to extremes and high impact events such as floods, storms, droughts and heat waves, including compound events; (2) demonstrate the applicability and added-value of such analyses (or tools based thereupon) for stakeholders and practitioners with a particular focus on insurance and adaptation in different sectors; and (3) foster discussions on new scientific methodologies, good practices and emerging standards between scientists and practitioners across disciplines and application areas. Papers related to all aspects of climate hazard and/or (economic) risk assessment and attribution covering all geographical areas are welcomed, regardless of whether they are focused on single hazards (risks), multiple hazards (risks), or a combination or cascade of hazards (risks). Contributions related to projects funded under EU H2020, Copernicus Climate Change Services (C3S), ERA4CS, JPI Climate and other larger scale climate service programmes are especially encouraged.
This session is endorsed by the European Climate Research Alliance (ECRA)’s Collaborative Programme on High Impact Events and Climate Change.

It has been shown that regional climate change interacts with many other man-made perturbations in both natural and anthropogenic coastal environments. Regional climate change is one of multiple drivers, which have a continuing impact on terrestrial, aquatic and socio-economic (resp. human) environments. These drivers interact with regional climate change in ways, which are not completely understood. Recent assessments all over the world have partly addressed this issue (e.g. Assessment of Climate Change for the Baltic Sea region, BACC (2008, 2015); North Sea Climate Change Assessment, NOSCCA (2011); Canada’s Changing Climate Report, CCCR (2019)).
This session invites contributions, which focus on the connections and interrelations between climate change and other drivers of environmental change, be it natural or human-induced, in different regional seas and coastal regions. Observation and modelling studies are welcome, which describe processes and interrelations with climate change in the atmosphere, in marine and freshwater ecosystems and biogeochemistry, coastal and terrestrial ecosystems as well as human systems. In particular, studies on socio-economic factors like aerosols, land cover, fisheries, agriculture and forestry, urban areas, coastal management, offshore energy, air quality and recreation, and their relation to climate change, are welcome.
The aim of this session is to provide an overview over the current state of knowledge of this complicated interplay of different factors, in different regional seas and coastal regions all over the world.

World-wide an increasing number of research projects focus on the challenges associated with changes in the Arctic regions. Whereas these often have a natural and physical science focus, this session focuses on trans-disciplinary approaches to study the multiple phenomena associated with global warming, especially but not exclusively in Arctic regions. Another focus is to understand better how to tackle these in large, trans-disciplinary research projects, initiatives and programs (e.g. HORIZON2020 Nunataryuk, INTAROS and the T-MOSAIC program of the International Arctic Research Council, NSF Navigating the New Arctic), as well as communicating results effectively to the public in terms of outreach and education. Contributions are invited, but are not limited, to the following themes:
• science communication, education and outreach tools, and co-production of knowledge
• integration of social and natural science approaches
• indigenous and collaborative approaches to adaptation and mitigation, equitable mitigation, and risk perception
• socio-economic modelling in relation to Arctic environmental change,
• examining the impacts of permafrost thaw and other phenomena on health and pollution as well as infrastructure (and consequences of the built environment).

One of the aims of this session is to bring together researchers from both social and natural sciences who are involved or interested in reaching out to stakeholders and the general public, and share successful experiences. Examples from past, ongoing and future initiatives that include traditional indigenous knowledge and scientific tools and techniques are welcome.

This session merged from

ITS5.9/EOS4.14
Trans-disciplinary aspects of researching permafrost thaw: science communication, integration, monitoring, modelling and risk perception
Co-organized by CL4/CR4/GM7/HS12/NH9
Convener: Peter Schweitzer | Co-conveners: Annett Bartsch, Susanna Gartler

EOS4.1
Where human and natural systems meet: promoting innovative tools for Arctic outreach and education
Convener: Terenzio zenone | Co-conveners: Frederic Bouchard, Stein Sandven, Ylva Sjöberg, Donatella zona

CR4.5
Towards collaborative frameworks for permafrost research that incorporate northern principles: challenges and opportunities
Convener: Peter Morse | Co-conveners: Ryley Beddoe, Hugh O'Neill, Ashley Rudy, Greg Sieme